In UMTS, a radio interface between a terminal and UTRAN (Universal Terrestrial Radio access Network) includes the following three main protocol layers.                physical layer (layer 1)        link layer (layer 2)        Radio Resource Control (RRC) layer        
The RRC layer plays a role to manage a signal between the UTRAN and a mobile object and a configuration of a resource for protocol layers 1 and 2 in a radio interface. The RRC layer provides a signal message to non-connection layers.
The UTRAN has large flexibility in management of a radio resource. This appears as various services depending on an activity level of a related mobile object in RRC protocol area. A main principal is to adapt allocation of the radio resource to the mobile object in any time in accordance with demand of traffic.
The RRC protocol has two modes, namely, an Idle mode, in which a voltage is applied to the mobile object but there is no RRC connection between the mobile object and the UTRAN, and a connection mode, in which the mobile object is RRC-connected to the UTRAN. The connection mode is mainly classified into four states, namely, CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH.
The CELL_DCH state is characterized by an allocation of a dedicated radio resource (one or more transmission channels of DCH (Dedicated Channel) type) to the mobile object. The dedicated resource is allocated for traffic of a real time type or for transmission of high-capacity data.
In the CELL-FACH state, no dedicated radio resource is allocated to the mobile object. In this state, common transmission channels (RACH: Random access channel, FACH: Forward access channel, and CPCH: Common Packet channel) are used for transmission between the terminal and the network. The CELL_DCH state is suitable for transmission of low-capacity data without restriction of a real time.
The CELL_PCH and the URA_PCH states are dormant state of the RRC protocol in a connection mode. Transition to the dormant state is controlled by the network after it has been found that lack of user traffic is prolonged, for example. In the dormant state, the mobile object is in a discontinuous receiving mode (a DRX for a discontinuous receiving) and its main activity is to monitor a paging channel and to manage mobility of the mobile object in the UTRAN. The RRC needs to return to the CELL_FACH state and carry out position determination update procedure in the UTRAN before restarting the user traffic.
Accordingly, in the CELL_PCH or the URA_PCH state, if the user traffic in a downward direction is indicated to the UTRAN, the UTRAN commands the mobile object to transit to the CELL_FACH state for restarting the traffic by sending a paging message to the mobile object. Then, the mobile object transits to the CELL_FACH state and carries out position determination update procedure (Cell Update) due to a response to the paging. After that, the user traffic can be restarted.
In the case of the traffic in an upward direction, the RRC layer of the mobile object transits to the CELL_FACH state and starts the Cell Update procedure due to the traffic restart on a route in the upward direction. Then, if this procedure is well achieved, the traffic will be restarted.
A specification of RAN WG group (release 5) of 3GPP (third Generation Partner Group) defines HSDPA (High Speed Downlink Packet Access) technology, which enables high-speed data transmission from a network to a terminal by allocating a resource of each channel to various users 500 times per second. The operation is carried out during a time slot between two packets in accordance with modulation and a bit rate determined by adaptation of a radio link.
In CDMA channel, it is referred again that all users use the same frequency band and each user is identified by one code. In the UMTS, a single code is allocated to each mobile object and this means that a resource of the channel is used by a single user. On the other hand, according to HSDPA technology, up to 14 codes can be allocated to each mobile object, so that all resources of one channel may be shared allowing dynamical allocation according to a demand of each mobile object at a certain transmission bit rate. This transmission bit rate may reach to 8 to 10 Mbps at a frequency band of 5 MHz in WCDMA down link. Such increase of a bit rate is derived from the fact that unlikely to the UMTS transmitting 2 bits information per “symbol” (or baud) using a QPSK modulation, the HSDPA further implements a 16QAM modulation for sending 4 bits per symbol. Further, in the UMTS, 10 to 20 milli-seconds elapse between transmission of two packets, however, in the HSDPA, the interval is shortened to 2 milli-seconds. Therefore, the traffic is accelerated. In addition, in the WCDMA, a base station is operated with transmission power for maintaining a certain quality, and according to the HSDPA technology, the base station adapts speed to transmission condition constantly. Further, the HSDPA technology introduces a new packet ACK mechanism. Generally, if a wrong packet arrives, a receiver eliminates it and requests retransmission of a correct packet. Although the HSDPA also requests retransmission, the HSDPA memorizes this. This is based on a principal such that, in the case that a wrong packet arrives, it is feared that the following packets are also wrong. The purpose thereof is to reproduce a correct packet from a plurality of wrong packet fragments.
Further, a specification of 3GPP (release 6) group integrates MBMS service (Multi-Broadcast/Multicast Service) into a 3G standard in order to provide broadcast of the same content to a plurality of destinations. At first, a configuration, in which a terminal is capable of receiving the broadcasted MBMS service, only when the terminal is in the condition of IDLE, CELL_PCH, URA_PCH, and CELL_FACH, is considered. After that, a configuration, in which a terminal is capable of receiving these services when the HSDPA receive channel is not used in the CELL_DCH state simultaneously, namely, when a receive channel R99 DCH is only used, is considered.
Due to introduction of the new HSDPA technology, the 3GPP group comes to define a new resource such as a new control channel (F-DPCCH) or the like, a new signal carrier wave and a voice transmission in the HSDPA channel. This means that the HSDPA receive channel is likely to be automatically allocated to the terminal in the CELL_DCH state. Here, an MBMS packet is more likely to be lost when the HSDPA receive channel is allocated. Therefore, the terminal may need to receive the MBMS packet at the second time or to carry out a correction using a point-to-point mechanism and thereby, battery life of the terminal is remarkably shortened.
As a result, if the HSDPA channel is allocated to the terminal, the terminal cannot effectively receive the MBMS service, a packet switch service (PS), and a (voice) circuit switch service (CS) at the same time. On the other hand, it has been more and more desired that the terminal can receive the service even when the terminal is in the CELL_DCH state.